How old is my Coleman furnace or air conditioner?

By Dana Whitlock. Updated October 2026. Widely documented.

The Coleman on your furnace has no connection to the camping lantern company today. The heating and cooling line licenses the name and uses York's serial code, so the date sits in the first four characters.

Units built from October 2004 on read cleanly to the month. Older ones use letters for both month and year, and the year letter repeats every 21 years, so you sometimes need one more clue to pick the decade. Many older units in manufactured homes wear a Coleman Evcon badge. They decode the same way in the tool above.

Where to find the label on a Coleman furnace

On a Coleman furnace, the rating plate sits inside the cabinet, behind the blower access door at the bottom front. York's 2001 recall notice describes the brand, model and serial as printed inside the removable front panel. On an outdoor condenser or heat pump, look on the side of the cabinet near the electrical access cover. Turn the furnace off at its service switch before you lift a front panel, and leave the lower blower door alone if the unit is running. A flashlight and a phone photo usually beat squinting; zoom in on the photo to read faded characters. Do not unscrew panels on the outdoor unit to hunt for the plate. It is on the outside.

How to read the code

For a unit built October 2004 or later, the serial starts with a plant letter, then a digit for the decade (0 for the 2000s, 1 for the 2010s, 2 for the 2020s), then a month letter, then the last digit of the year. Month letters run A through H for January to August, then K, L, M and N for September to December, since I and J are skipped. For older units (1971 through September 2004), the second character is the month letter, the third is a year letter, and the fourth is a product-type letter that has nothing to do with the date. Ignore a stray prefix in parentheses, such as (S), if the plate shows one.

Real serials in this code

When the format changed

Year letters A through N each stand for two possible years, 21 years apart. A means 1971 or 1992, K means 1980 or 2001, N means 1983 or the first nine months of 2004. Letters P through Y only ever meant 1984 to 1991, so those are unambiguous. A Coleman label like EBKM041257 shows the problem: K could be 1980 or 2001, and an inspector on InterNACHI placed that furnace in 2001. To break the tie on your own unit, compare the refrigerant and efficiency rating printed on the plate against the two candidate years, look for a printed manufacture date, ask for the original installation invoice, or check the age of the house. A 1980 furnace in a house built in 1998 is not likely.

Who makes Coleman

Coleman Corporation of Wichita spun its heating and cooling line off around 1990 under the Coleman Evcon name, and York bought that line in the mid-1990s. In 2000 York dropped the Evcon tag and went back to plain Coleman, according to ACHR News, and at the time roughly half of Coleman output went into manufactured housing. Coleman shares its serial code and factories with York and Luxaire. The residential business that builds all three was owned by Johnson Controls until Bosch completed its purchase on July 31, 2025. Coleman equipment is sold through its own distributor network to independent installers, separate from the York and Luxaire channels.

How sure is this?

Widely documented. Coleman doesn't publish this code; it comes from recall notices, service literature and inspector references. We tested the jci york rules against 35 serials, 8 of them with a date known from a recall notice, a printed label date or the maker. None decoded to a wrong year; codes whose year mark repeats show every possible reading. Always confirm with Coleman's warranty page before you spend money on the answer.

Quick notes

• If the plate says Coleman Evcon, read it exactly like a Coleman serial.
• In a manufactured home, the furnace may be a downflow model tucked into a hall closet; the plate is still behind the lower door.
• A serial starting with W points to the Wichita plant, which also built many Coleman condensers.
• Ask the installer whether the system was registered; a registration record carries the install date and ends any decade guessing.